Wave apparatus



B. L. STEELE WAVE APPARATUS Oct. 18, 1932.

Filed Aug. 25, 1930 52116711307 irxenton L. m

Sie ale placements,

Patented Oct. 18, 1932 UNTTED STATES ATEr BRENT-N Ls'rEELnor PULLMAN, wasrrmsron WAY-E APPARATUS Application filed August 25, 1930.

- accompanyingw drawing,in which Fig. 1 is a: view representing the formation ofstanding waves in a vibrating cord, the far end ofwhich is fixed;

Fig. 2 is a View illustrating progressive waveswhich are obtainable when the far end of the cord is supported by the receiving apparatus of this invention, the successive crests in the figure representing positions of the same wave form at the end of succeeding intervals .of'time; V

Fig.3 is a perspective view somewhat diagrammatic, illustrating the general organization of thewaVe-apparat'us V n Fig. 4 isa front view of the receiving apparatus, illustrating the application of the mag netic brake to the'spring pendulum; and

Fig. 5 is an end, elevational view of the same.

When a-cord'fixed at one endand held relatively taut is given a series of quick disa. train of waves will be set up which will travel to-the far end of the cord and be reflected back in reverse phase. If the displacements are continued at a uniform rate, standing. waves will be produced with the formation of nodes and antinodes at intervals of a half Wave length, respectively, as shown in Fi 1.

If the far end of the cord, instead of being fixed,.is secured to a support which is capable of absorbing the energy delivered by the wave trains at exactly the same rate at which it is carried by the wave, no reflections will take place and the result, in eifect, is to have a cord of infinite length. Inlother words, if a receiving apparatus is provided which will carry the far end of the cord .over the same path thatit would be carried were the cord of infinite length, it is possible to produce progressive waves for such periods of time that their characteristics maybe accurately ob- Serial No. 477,537.

served. This is shown diagrammatically in Fig.2. 7

In Fig. '3, there is illustrated one embodiment of this invention, but this specific illus tration and the corresponding specific description are for the purpose of disclosure only and are not intended to'impose limitat-ions on the scope of. the invention which is indicated by the appended claims.

The transmitting apparatus comprises a w constant speed motor 10 operating through a variable speed device 11 to rotate a driving wheel 12 which is provided with a pit man connection 13 to a. indicated at-l t. Inasmuch as this part of the invention is but an expedient to produce a uniform train of waves, and is well known, a further description is deemed unnecessary.

In the present instance, the 'medium :2 through which the waves are passed comprises a heavy walled rubber tube 15 securely knotted at one end 16 to the cross head of the wave propagating mechanism and at the other end to a spring pendulum hereinafter I to be described. The tube may be filled with mercury or some other heavy substance to give it suitable weight for making experiments.

crosshead, generally Reflection of the waves at the far end of the tube is avoided by employing a spring pendulum having itsnatural period the same as thatof the driving force at the power end of the tube, and equipping it with a magnetic brake which may be varied in intensity so as to exactly balance the energy delivered to the pendulum by the wave. Two resilient rods 17 are secured in a clamping block 18 mounted on a fixed support 19 and terminate at their lower end in a cylindrical block 20 Y which carries a flat insulating piece 21 in which are embedded a pair of coils-22. The rods are arranged in the form of a truss, one behind the other so as to stiffen the spring pendulum'at rightangles to its plane of oscillation. of the rods are adjustable with respect to the clamping block 18 so as to vary the efiective length of the pendulum and thus make it possible to give the pendulum a predetermined natural period of oscillation. The

Preferably, the upper ends tube 15 is secured to the cylindrical block 20 of the pendulum.

An electromagnet 23 having its poles on opposite sides of the coils 22 and in juxtaposition thereto is fed by a battery or other source of current 24, in series with a variable resistance 25 and an ammeter 26.

When the pendulum is tuned to the period of the driving mechanism, it will pick up the energy from the waves and will start to oscillate. The amplitude of the oscillations will gradually increase until they exactly coincide with the natural movement of the wave, at which time no reflection of the wave train will occur. The energy which is being carried by the waves will, however, cause the oscillations of the pendulum to gobeyond the natural amplitudes of the waves, which, unless restrained, will set up interfering reflected waves.

This effect is counteracted by the magnetic brake which may be controlled in intensity by the rheostat 25. As the field strength of the electromagnet is increased, the magnetic brake effect is correspondingly increased, with the result that a proper manipulation of the rheostat, the resistance of the coils 22 passing through the magnetic field may be made to exactly counterbalance the force which is tending to carry the pendulum beyond its desired swing. Stated in other words, the energy absorbed by the electromagnetic brake must be adjusted so that it exactly equals the diilerence between the energy given to the tube at the power end and the energy dissipated in the length of the tube because of internal resistance or friction and other force constants.

In order to give some visual evidence of the absorption of energy by the receiving apparatus, a small incandescent lamp 2'? may be connected in series with the coils 22 so that when the pendulum is oscillating in the magnetic field, an induced alternating cur rent will be set up which will illuminate the lamp.

It will be understood that the entire apparatus may be modified in various elements and details without departing from the spirit of the invention. For example, it is possible to accomplish the absorption of the wave energy by an apparatus similar to the transmitting mechanism and operated in synchronism therewith. Or the desired results may be accomplished by substituting other damping means for the electromagnetic brake, such as a dash pot. In other words, the gist of this invention is to provide some device by which the energy given to the tube at one end is transmitted by means of travelling waves through the tube and is converted into some kind of work at the other end.

The mercury filled rubber tube is'only one example of a medium in which the waves may be propagated. The tube itself could be weighted at equally spaced intervals from end to end or any material of suitable density could be employed, or the tube could be supported throughout its length on a series of equally spaced reeds or pendulums.

The operating characteristics of the different media will,of course, vary depending upon certain factors, such as the tension applied to the material, its inertia, and its internal structure.

I claim as my invention: 7

1. In a wave apparatus, a transmitting mechanism including a constant speed motor,

a variable speed device, and a crosshead, a cord secured at one end to the crosshead and receiving wave impulses therefrom, and adjustable means at the other end of the cord for receiving the waves and absorbing their energy at exactly the rate at which the energy was imparted to the cord by the transmitting 95 mechanism.

2. In a wave apparatus,'a flexible medium for carrying a wave, means for settingup visible, transverse waves in the medium, and means for dissipating the energy to avoid a reflection of the waves. 7

3. In a device of the class described, a transmitting mechanism, a medium adapted to receive wave impulses from the said mechanism, and a receiving apparatus including a pendulum and a magnetic brake.

4; In a wave apparatus including a transmitting mechanism and a flexible cord, the combination of a spring pendulum connected to the receiving end of the cord and carrying a conductor, an, electro-magnet having its poles on oppositesides of the pendulum conductor in juxtaposition thereto, and means for controlling the current through th'e'electro-magnet. I c

5. In a'wave apparatus including a transmitting mechanism and a wave carrying medium, the combination of a pendulum adapted to have its period tuned to that of the transmitting mechanism, a conductor carried 1 by the pendulum, and means for creating a magnetic field of controllable intensity in the path of the conductor.

6. A receiving apparatus for wavetrains comprising a pendulum mounted to swing in one plane, a coil carried by the pendulum and means for creating a magnetic fieldin the path of said coil at right angles to the swing of the pendulum.

7 A receiving apparatus for wave trains comprising a pendulum mounted to swing in one plane, a coil carried by the pendulum, means for creating a magnetic field in the path of said coil at right angles to the swing of the pendulum, and means for controlling the intensity of the magnetic field.

8. A receiving apparatus for wave trains comprising a pendulum mounted to swing in one plane, a coil. carried by the pendulum, means for creating a magnetic field in the 139 path of said coil at right angles to the swing of the pendulum, means for controlling the intensity of the magnetic field, and an indicator lamp in series with the coil.

9. A receiving apparatus for wave trains of uniform frequency comprising a support for the wave medium adapted to be tuned with its amplitude and natural period coincident with the amplitude and period of the Waves.

10. In a device of the class described, a wave transmitting mechanism, heavy walled mercury filled tube connected at one end to the said mechanism, and a support for the other end of the tube adapted to reciprocate at the rate and amplitude of the wave oscillations.

11. In .a wave apparatus including a transmitting mechanism and a wave medium, the combination therewith of a spring pendulum braced at right angles to its plane of oscillation and connected to the receiving end of the wave medium, a coil carried by the pendulum, an electromagnet adapted to set up a magnetic field in the path of the coil, and means for controlling the intensity of the magnetic field.

12. In a wave apparatus including a transmit-ting mechanism and a wave carrying medium, the combination of a pendulum having its period adapted to be tuned to that of the transmitting mechanism, a conductor carried by the pendulum, means for creatin a magnetie field of controllable intensity in the path of the conductor, and an indicator electrically operated by the induced current in the conductor to show the absorption of energy.

13; In a wave demonstration apparatus, a flexible medium for carrying a wave, means for setting up uniform transverse waves in the medium which are readily visible to the naked eye, a receiving apparatus, and means for dissipating the energy of the wave at the receiving apparatus at a rate which will avoid a reflection of waves.

14. In a wave demonstration apparatus, a medium for carrying a wave, means for setting up visible unifoi; Y a---wiiarfliflffiiiiibhi to which the waves are transmitted by the medium, means for ad justing the natural period of the vibrating member to correspond with the period of the waves which are propagated along the medium, and means for dissipating the energ received by the vibrating member to avoid a reflection of waves.

15. In a wave apparatus, a wave medium for conducting waves along the same, a support for one end of said medium, means associated with said support for dissipating the energy of the wave conducted along said medium at a rate suficient to avoid its reflection over the medium.

16. In a wave demonstration apparatus, a

flexible medium for carrying a wave, means for setting up uniform waves in the medlum which are readily visible to the naked eye, a

receiving apparatus, and said apparatus having a means for dissipating the energy of the wave at the receiving apparatus at a rate which will avoid reflection of waves.

17. In a wave apparatus for demonstrating the properties of continuously travelling V 

